⁵⁶Mn, ⁶⁰Co, ¹⁸F and ²²Na activity measurements by coincidence technique at VNIIM

For modernization of the Russian national activity standard at the Ionizing Radiation Department of the D.I. Mendeleyev Institute for Metrology, a prototype 4π(LS)-γ(NaI) coincidence arrangement was created, and applied to the standardization of long-lived ⁶⁰Co and ²²Na and short-lived ⁵⁶Mn and ¹⁸F. Efficiency variation was performed using "grey filters", high voltage variation and variation of low threshold. The main metrological characteristics of the setup were determined: long-term stability, background, dead time, resolution time and temperature dependence. The results obtained have practical applications. The ¹⁸F solution with well-known activity is required for calibration of ionizing chamber used in nuclear medicine. The ⁵⁶Mn is used for calibration of manganese bath equipment used in neutron laboratory. The results obtained are in good agreement with 4πγ(NaI)-counting and 4πβ(PC)-γ(NaI) methods of Russian national radioactivity standard. The combined uncertainty (k=2) of results was estimated in the range 1–2%. - Highlights: • A prototype 4π(LS)-γ(NaI) coincidence counting system developed at VNIIM • Activity concentrations of solutions of ⁶⁰Co, ²²Na, ¹⁸F and ⁵⁶Mn were measured • 4πβ(Cherenkov)-γ(NaI) coincidence method was chosen for ⁵⁶Mn activity concentration measurements